Medium feeding device, image reading apparatus, and recording apparatus

Abstract

A medium feeding device includes an imaging unit which images a medium tip end portion from a position of facing a face of the medium on a downstream side of a nipping position of the medium using a feeding unit and a separating unit; and a determining unit which determines whether or not there is transport disorder by evaluating a state of a boundary between a path member which forms a medium transport path and a medium tip end from image data obtained by the imaging unit, in which the determining unit sets a rectangular determining region including at least a part of the boundary with respect to the image data, and determines whether or not there is transport disorder based on a length of a boundary in the determining region.

What is claimed is: 
     
       1. A medium feeding device comprising:
 a medium mounting unit on which a medium is mounted; 
 a feeding unit which feeds the medium from the medium mounting unit; 
 a separating unit which separates the medium between the feeding unit and the separating unit by nipping the medium; 
 an imaging unit which images a medium tip end portion from a position of facing a face of the medium on a downstream side of a nipping position of the medium using the feeding unit and the separating unit; and 
 a determining unit which determines whether or not there is transport disorder by evaluating a state of a boundary between a path member which forms a medium transport path and a medium tip end from image data obtained by the imaging unit, 
 the determining unit obtaining averaged brightness as a value in which brightness of a pixel group which goes along the medium width direction as a direction orthogonal to the medium transport direction is averaged along the medium transport direction from the image data, 
 the determining unit being configured to obtain a first threshold value as a threshold value with respect to the averaged brightness for determining a present state of a medium, and a second threshold value as a threshold value for determining an absent state of the medium which is lower than the first threshold value, and 
 the determining unit determining whether or not there is the transport disorder based on highs and lows of a value with high brightness with respect to the first threshold value, and highs and lows of a value with low brightness with respect to the second threshold value, in the averaged brightness at both ends of a determining range including at least a part of the boundary. 
 
     
     
       2. The medium feeding device according to  claim 1 ,
 wherein the determining unit sets a rectangular determining region including at least a part of the boundary with respect to the image data, and determines whether or not there is the transport disorder based on a length of the boundary in the determining region. 
 
     
     
       3. The medium feeding device according to  claim 2 ,
 wherein the determining unit determines whether or not there is the transport disorder based on an angle of the boundary in the determining region to a medium width direction as a direction orthogonal to the medium transport direction. 
 
     
     
       4. The medium feeding device according to  claim 1 ,
 wherein, in a case in which the determining unit determines that there is the transport disorder, the feeding unit is stopped. 
 
     
     
       5. The medium feeding device according to  claim 1 , further comprising:
 a feeding roller which configures the feeding unit, and is rotatably driven by a driving source; 
 a separating roller which configures the separating unit, and is rotated in a driven manner by being in contact with the feeding roller; and 
 a detecting unit which detects a changing amount of a position of at least any one of the feeding roller and the separating roller with respect to the other roller. 
 
     
     
       6. The medium feeding device according to  claim 5 ,
 wherein the detecting unit includes a driven roller which rotates in a driven manner by being in contact with the feeding roller or the separating roller as a target for detecting the changing amount of a position, a roller support member which rotatably supports the driven roller and is configured to swing around a swing fulcrum, and an angle detecting sensor which detects a swing angle of the roller support member. 
 
     
     
       7. An image reading apparatus comprising:
 a reading unit which reads a medium; and 
 the medium feeding device according to  claim 1 . 
 
     
     
       8. A recording apparatus comprising:
 a recording unit which performs recording on a medium; and 
 the medium feeding device according to  claim 1 .